Can you share a “killer” warm-up or exercise?

I am set to do several teaching demos in the coming weeks as part of a major job search. In each case I’ll be working with someone else’s high school (and a couple of middle school) chorus during a regular rehearsal. They will have never seen me before, and I’ll know next to nothing about them. The usual!

While I will be well prepared, and will have lots of great warm-ups and other activities of my own up my sleeve, I wonder if any of you would be willing to share a “killer” warm-up or exercise with me (and with the other folks here on ChoralNet)?

Here are my three criteria for choosing what kinds of exercises I’ll use:

1: Whatever I do with them must be fun/enjoyable/engaging for the singers. Ideally, it would be both fun to do while it’s happening, and just as important, rewarding in that we achieve something - some improvement - that every one of them can hear and appreciate. I want to leave them thinking “Wow - we’re better!” and “I want to do more of that!”

2: The warm-up or exercise should demonstrate that not only am I a fun teacher, I know my stuff, and can improve the students’ performance both quickly and tangibly. I want to leave the administrators thinking “This guy is good - he has high standards and knows how to get real results in a way that students enjoy”

3. The warm-up or exercise should be pretty “fool-proof”; i.e., not so complicated or difficult that a small chorus, or an inexperienced chorus, or a just-after-lunch chorus could really blow it, resulting in a big FAIL. [I have an exercise I love that involves complicated chord progressions and has only worked with about 1/3 of the groups I’ve tried it with. I will not be using that one.]

My job will be to assess where the issues lie with the group, assess what they can handle and respond to, choose the appropriate exercises, and use my people/leadership skills to lead them through it successfully, listening and responding to what I hear and see.

So, does anyone have a “magical, knocks ‘em dead every time, make me look like Superman/woman” exercise or warm-up to share?